He is now considering offering a reward for information leading to the identification of the culprit, but only if members of the public do not have a conscience.
''People must know who's doing it,'' he said.
Delta contractors planted $10,000 worth of toothed lancewood and native tussock on the strip last week, and a vehicle was intentionally driven over the new plantings on Wednesday night.
''This is just such a mindless waste of everyone's money,'' he said.
''We don't have limitless money to spend. It's important to make the city look as attractive as we can for residents and visitors alike, and here we've got these brainless morons who think it's acceptable to drive over plantings and trees - in this case, $10,000 worth.''
Mr Benson-Pope said it was an ongoing issue.
There had been previous instances over a number of years where dozens of trees had been destroyed by vehicles being driven over them on Portsmouth Dr, he said.
''There were really extensive plantings along the median strip and along both sides of Portsmouth Dr, and they were consistently and regularly driven over by four-wheel-drives.
''It's frustrating.
''It's obviously 'Ha ha, look how clever I am. I'm doing it because I can, and isn't it fun'.
''The great irony is, everyone is paying for it, including the culprits.
''I'm [angry] about this one because I approached council parks to get this work done, because of some complaints that came direct to me about the state of the median.
''And now all the good work has been blown away within a week.''
Mr Benson-Pope said the council had to make sure damage like this could not be repeated in the future.
''They have to be protected so people can't drive over them and destroy thousands of dollars of ratepayers' funds.
''Some large pieces of bluestone or substantial staking is enough to stop the sort of damage that's been going on.''
He hoped members of the community would come forward with information about the culprits soon. But if they did not, he would raise the issue at the next committee meeting.
He said the idea of offering a reward for any information that leads to the conviction of the offenders would be raised.
-Dunedin police (03) 471-4800, Crimestoppers 0800 555-111.
